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My new to me '91 300 SEL has a humming noise coming from the rear. Low pitched. Guessing it might be the fuel pump. Is that a usual noise? Nothing wrong with fuel supply. Sure it isn't tire hum. More 'electric'. My old MG's had a fuel pump sound but was a 'click' as it was a true pump. Any ideas? ps- you sure helped me change the light in the shift boot. Great directions. You guys know your stuff!
 

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1991 500SEC Euro, 1987 560SEC Federal
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Hi Gordo,

The hmmmmm sound you hear will certainly be the electric fuel pump which in our MS, is a motor driven rotary pump. Quite normal as deathrattle stated, though I'm in agreement with you in regards to the MG pump which was on most models since the 1930s, a diaphragm pushed back & forth with an electric solenoid & made by S.U. hence the clicking sound you describe. The points would fail on these babies rather often, making them relatively unreliable overall.
There is one of those SU pumps mounted in the boot of my MK1 Jag today.

Cheers, MBL
 

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1991 500SEC Euro, 1987 560SEC Federal
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5,682 Posts
Hey there deathrattle,

40 years ago, now there's a scary thought, I had a 1960 3.8 MK2 which was great learning experience...... Yup, took me several weeks/month to fathom the diabolical SU mystery 'intermittent failure to proceed' syndrome! Well, among other things...........

You had a Seven? You lucky stiff!

[:D] MBL

A Caterham 7 below & my 3.4 cat.
 

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